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Old Sep 18, 2008, 12:13 PM
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Hamburg, Germany
Joined Nov 2006
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New Project: Advice Needed

Hi all,
I am new to flying wings (coming from 3d Foamies and 3d Helis).
So i will build this from depron and glass fibre.
The depron will be sandwichen in multiple layers, to approximate the shape of the airfoil. Then all edges will be sanded to achieve a smooth round surface.
Finally the whole structure will be covered with 25g/m^2 glassfibre.
span:1.50m
weight: under 400 gram is the aim
I am using a 30g outrunner togehter with a 12 amp esc on 3s 1000mah.
Planned is a 9''*5'' folding prop.

So my question is:
If i equip the Wingerlets with control surfaces, will that make the plane by yaw controllable??
Does any of you has eyperiences with rudder winglets?

Thanks for help!
Marvin
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Old Sep 18, 2008, 01:03 PM
Ace
atmk's Avatar
Joined Jan 2007
339 Posts
yes!
though i have never seen it done in an rc aircraft
full size airplanes with rudders on the wiglets deflect the inside rudder much more because of the difference in turning radius
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Old Sep 18, 2008, 01:50 PM
D'oh.. Dumb Left Thumb
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London, UK
Joined Nov 2006
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check out the Graupner Canary
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Old Sep 18, 2008, 02:56 PM
Registered User
Hamburg, Germany
Joined Nov 2006
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Hey!
I just build a scaled model of my plane out of plain 3mm depron 0.5 m span.
No matter where i set cg, i just can't get it pitch stable!
It will glide for like 1m and then start to pitch up or down very rough!
If it's the same on a larger scale i will rather build a conventional glider!
Need help on this one too please!
I heard that on real flying wings, the chord on the outer span has negative twist inorder to achieve a pitch stable behaviour.
Do you do the same thing on rc planes?
greetings,
Marvin
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Old Sep 18, 2008, 07:21 PM
Herk
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Virginia USA
Joined Jun 2007
1,637 Posts
Marvin,
You do need some negative twist in the outer wing of your test model. That's not so much for stability as it is for trim. Your flat depron model needs that or some elevon surfaces out near the tips that are trimmed up just a bit. Then you can add some weight until it glides in a reasonably stable flight. Since you don't have RC in your test bed, it might glide better if it had just a bit of dihedral. Up to a point more sweep makes it easier to balance and trim. Yours looks to me like it could use just a bit more.

Flying it as an electric powered model, I doubt that you will need rudder control. You didn't draw any control surfaces - you will need elevons outboard on the wings. Flaps inboard could help with landings but aren't absolutely necessary.
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Old Sep 19, 2008, 05:06 AM
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Kent, UK
Joined Nov 2004
856 Posts
Marvin

that's a great looking design, I hope you can keep the whole thing light enough so you don't run into any rigidity issues with that taper

keep us posted
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Old Sep 19, 2008, 01:55 PM
Registered User
Hamburg, Germany
Joined Nov 2006
208 Posts
Hey Guys,

I want to have some glider airplane for chill flights.
So i changed the design but have not yet drawn anything. It's all in my head right now. Changes:

-more like lifting body design
-less aspect ratio so it is not too sluggish on roll and the structure will have
more rigidity
-dihedral on the outer wings (those that don'belong to the body... if you know
what i mean...)
-downward facing winglets, no rudder control

The good thing about this project is that its exciting to design something uncommon.
The bad thing is that i dont know how it will fly.
Will post new CAD drawing tomorrow
greetings,
Marvin
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Last edited by somt1033; Sep 19, 2008 at 02:11 PM.
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Old Sep 19, 2008, 06:22 PM
Registered User
Hamburg, Germany
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shall i use symmetrical airfoil?
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Old Sep 19, 2008, 07:26 PM
Herk
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Virginia USA
Joined Jun 2007
1,637 Posts
Marvin, Bill Northrop said all flying wings should use symmetrical airfoils.

However the best airfoils to use depend on the layout of the wing - and the aircraft designed purpose. Do your drawing first and describe it's purpose then let's see what airfoils might work for you. The main design purpose is the flight mission that you intend for this plane. If it's to be a speed record challenger, the airfoils will be different than if it's to be a thermal soaring sailplane. Think about what you want this aircraft to be able to do.
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Old Sep 19, 2008, 09:36 PM
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that thing is sweat. could you make it a push-pull set up. In line thrust would rule
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Old Sep 20, 2008, 06:51 AM
Registered User
Hamburg, Germany
Joined Nov 2006
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New Drawings

Yo!
here are the new sketches..
detailed ones are in the works.
i was inspired by the killer bee uav
Marvin
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Old Sep 20, 2008, 07:10 AM
Herk
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Virginia USA
Joined Jun 2007
1,637 Posts
Hello Marvin,

Nice looking layout. Have you decided if this is to be a glider or a general purpose sport flyer? In other words, what will be the mission or purpose of this model? Have you given thought to where the control surfaces will be located?

I think you will like to see these pictures of the Northrop N1M prototype.
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Old Sep 20, 2008, 08:52 AM
internet gadfly
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Colorado
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If you skew the axis of the bend like this you'll get the effect of washout without having to twist the wing.

--Norm
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Last edited by nmasters; Sep 20, 2008 at 08:55 AM. Reason: forgot the picture
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Old Sep 20, 2008, 09:04 AM
Herk
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Virginia USA
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Norm -- great observation :-)
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Old Sep 20, 2008, 12:05 PM
Registered User
Hamburg, Germany
Joined Nov 2006
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Quote:
Originally Posted by nmasters
If you skew the axis of the bend like this you'll get the effect of washout without having to twist the wing.

--Norm
Thanks alot for that advice!

But i decided to do the whole outer wing as a wingeron design.
So the wohle surface will be deflectable and i can twist it anyways.
Marvin
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